System and method for sterilizing a lumen device

ABSTRACT

A system and a method for sterilizing a lumen device involve a container in a chamber and a source of germicide. The container has an interface separating the container into two compartments and a communication port which provides fluid communication between the container and the chamber. The lumen device extends across the interface, and the two compartments are in fluid communication with each other through the lumen device. The lumen device is sterilized when the germicide flows from compartment to compartment through the lumen device.

[0001] This application is a continuation of application Ser. No.09/643,336, filed Aug. 22, 2000, which is a continuation of applicationSer. No. 09/105,491, filed Jun. 26, 1998, now U.S. Pat. No. 6,174,502,which is a divisional of application Ser. No. 08/833,375, filed Apr. 4,1997, now U.S. Pat. No. 5,961,921.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] This invention relates to a process for using a source ofperoxide and negative pressure to sterilize articles such as medicalinstruments, and more particularly, to methods which include the step ofcontacting the articles or the diffusion-restricted environmentcontaining the articles with a source of peroxide prior to exposure tonegative pressure or negative pressure combined with plasma.

[0004] 2. Description of the Related Art

[0005] Medical instruments have traditionally been sterilized usingeither heat, such as is provided by steam, or a chemical, such asformaldehyde or ethylene oxide in the gas or vapor state. Each of thesemethods has drawbacks. Many medical devices, such as fiberoptic devices,endoscopes, power tools, etc. are sensitive to heat, moisture, or both.Formaldehyde and ethylene oxide are both toxic gases that pose apotential hazard to healthcare workers. Problems with ethylene oxide areparticularly severe, because its use requires long aeration times toremove the gas from articles that have been sterilized. This makes thesterilization cycle time undesirably long.

[0006] Sterilization using liquid hydrogen peroxide solution has beenfound to require high concentration of sterilant, extended exposure timeand/or elevated temperatures. However, sterilization using hydrogenperoxide vapor has been shown to have some advantages over otherchemical sterilization processes (see, e.g., U.S. Pat. Nos. 4,169,123and 4,169,124). The combination of hydrogen peroxide with a plasmaprovides certain additional advantages, as disclosed in U.S. Pat.4,643,876, issued Feb. 17, 1987 to Jacobs et al. U.S. Pat. 4,756,882,issued Jul. 12, 1988 also to Jacobs et al. discloses the use of hydrogenperoxide vapor, generated from an aqueous solution of hydrogen peroxide,as a precursor of the reactive species generated by a plasma generator.The combination of hydrogen peroxide vapor diffusing into closeproximity with the article to be sterilized and plasma acts to sterilizethe articles, even within closed packages. Further, these methods ofcombining hydrogen peroxide vapor with a plasma, while useful in “open”systems, have been found to be inadequate to effect sterilization inarticles having diffusion-restricted areas, since the methods aredependent upon diffusion of the sterilant vapor into close proximitywith the article before sterilization can be achieved. Thus, thesemethods have been found to require high concentration of sterilant,extended exposure time and/or elevated temperatures when used on long,narrow lumens. For example, lumens longer than 27 cm and/or having aninternal diameter of less than 0.3 cm have been particularly difficultto sterilize. Thus, no simple, safe, effective method of sterilizingsmaller lumens exists in the prior art.

[0007] The sterilization of articles containing diffusion-restrictedareas, such as long narrow lumens, therefore presents a specialchallenge. Methods that use hydrogen peroxide vapor that has beengenerated from an aqueous solution of hydrogen peroxide have certaindisadvantages, because:

[0008] 1. Water has a higher vapor pressure than hydrogen peroxide andwill vaporize faster than hydrogen peroxide from an aqueous solution.

[0009] 2. Water has a lower molecular weight than hydrogen peroxide andwill diffuse faster than hydrogen peroxide in the vapor state.

[0010] Because of this, when an aqueous solution of hydrogen peroxide isvaporized in the area surrounding the items to be sterilized, the waterreaches the items first and in higher concentration. The water vaportherefore becomes a barrier to the penetration of hydrogen peroxidevapor into diffusion restricted areas, such as small crevices and longnarrow lumens. One cannot solve the problem by removing water from theaqueous solution and using more concentrated hydrogen peroxide, since,among other reasons, concentrated solutions of hydrogen peroxide greaterthan 65% by weight can be hazardous due to the oxidizing nature thereof.

[0011] U.S. Pat. 4,952,370 to Cummings et al. discloses a sterilizationprocess wherein aqueous hydrogen peroxide vapor is first condensed onthe article to be sterilized, and then a source of vacuum is applied tothe sterilization chamber to evaporate the water and hydrogen peroxidefrom the article. This method is suitable to sterilize surfaces,however, it is ineffective at rapidly sterilizing diffusion-restrictedareas, such as those found in lumened devices, since it too depends onthe diffusion of the hydrogen peroxide vapor into the lumen to effectsterilization.

[0012] U.S. Pat. 4,943,414, entitled “Method for Vapor Sterilization ofArticles Having Lumens,” and issued to Jacobs et al., discloses aprocess in which a vessel containing a small amount of a vaporizableliquid sterilant solution is attached to a lumen, and the sterilantvaporizes and flows directly into the lumen of the article as thepressure is reduced during the sterilization cycle. This system has theadvantage that the water and hydrogen peroxide vapor are pulled throughthe lumen by the pressure differential that exists, increasing thesterilization rate for lumens, but it has the disadvantage that thevessel needs to be attached to each lumen to be sterilized. In addition,water is vaporized faster and precedes the hydrogen peroxide vapor intothe lumen.

[0013] In U.S. Pat. No. 5,492,672, there is disclosed a process forsterilizing narrow lumens. This process uses a multicomponent sterilantvapor and requires successive alternating periods of flow of sterilantvapor and discontinuance of such flow. A complex apparatus is used toaccomplish the method. Because flow through of vapor is used, closed endlumens are not readily sterilized in the process.

[0014] Thus, there remains a need for a simple and effective method ofvapor sterilization of articles having areas where diffusion of thesevapors is restricted, such as long, narrow lumens.

SUMMARY OF THE INVENTION

[0015] One aspect of the present invention relates to a method forsterilizing an interior of an article with a diffusion restricted area,such as an article having a lumen. The method includes the steps ofcontacting the interior of the article with a source of peroxide, andexposing the article to negative pressure for a time period sufficientto effect complete sterilization. In one embodiment, the source ofperoxide comprises a liquid or condensed vapor. In another embodiment,the source of peroxide comprising a liquid comprises hydrogen peroxideor peracetic acid. In another embodiment, the source of peroxidecomprising a condensed vapor comprises hydrogen peroxide or peraceticacid vapor. If the exposing step is conducted for 1 hour at 40° C. and10 torr, and the source of peroxide comprises 1 mg/L hydrogen peroxide,the diffusion restricted area preferably retains 0.1 7 mg/L or morehydrogen peroxide, or retains 17% or more of the hydrogen peroxideplaced therein after the exposing step. In certain preferredembodiments, the diffusion- restricted area has the same or morediffusion restriction than provided by a lumen 27 cm in length and aninternal diameter of 3 mm, or has the same or more diffusion restrictionthan provided by a lumen having a ratio of length to internal diametergreater than 50. The source of peroxide is preferably at a concentrationof less than 25% by weight. The contacting step can be performed bydelivery via a method such as injection, static soak, liquidflow-through, aerosol spray, condensation or physical placement. In apreferred embodiment, the diffusion-restricted area is a lumen at least27 cm in length and having an internal diameter of no more than 3 mm,more preferably having an internal diameter of no more than 1 mm. Theexposing step is preferably performed for 60 minutes or less, and ispreferably performed at a pressure less than the vapor pressure ofhydrogen peroxide. Thus, the preferred pressure range under conditionsof the present invention is between 0 and 100 torr. In one particularlypreferred embodiment, the pressure is approximately 10 torr and theexposing step is conducted at a temperature of approximately 23° C. toapproximately 28° C. The exposing step can include the step of heatingthe article, such as by heating the chamber in which the exposing stepoccurs. The chamber can be heated to about 40° C. to about 45° C.Alternatively, the source of peroxide can be heated, such as to atemperature of about 40° C. to about 45° C. Optionally, the step ofexposing the device to a plasma can be conducted during the step ofexposing the device to negative pressure. In one embodiment employingexposure to plasma, the method is performed within a first chamber andthe plasma is generated in a second, separate chamber. This embodimentfurther comprises the step of flowing the plasma into the first chamber.Advantageously, the contacting and/or exposing steps of the method canbe repeated one or more times.

[0016] Another aspect of the present invention relates to a method forsterilizing an interior and an exterior of an article. This methodincludes the following steps: contacting the article with a source ofperoxide; and placing the article in a diffusion-restricted environment.The contacting and placing steps can be performed in either order. Thesesteps are followed by exposing the diffusion-restricted environment tonegative pressure for a time period sufficient to effect completesterilization. The contacting step can be performed both before andafter the placing step. If the exposing step is conducted at 40° C. and10 torr, and a source of peroxide comprising 1 mg/L of hydrogen peroxideis introduced, the diffusion restricted environment preferably retains0.17 mg/L or more hydrogen peroxide after the exposing step, or retains17% or more of the hydrogen peroxide placed therein after the exposingstep. The exposing step can include the step of heating the article,such as by heating the chamber in which the exposing step occurs or byheating the source of peroxide. In certain preferred embodiments, thediffusion-restricted environment has the same or more diffusionrestriction than provided by a single entry/exit port of 9 mm or less ininternal diameter and 1 cm or greater in length, or is sufficientlydiffusion restricted to completely sterilize a stainless steel bladewithin a 2.2 cm by 60 cm glass tube having a rubber stopper with a 1 mmby 50 cm stainless steel exit tube therein at a vacuum of 10 torr forone hour at 40° C. In one embodiment, the source of peroxide comprises aliquid or condensed vapor. In another embodiment, the source of peroxidecomprising a liquid comprises hydrogen peroxide or peracetic acid. Inanother embodiment, the source of peroxide comprising a condensed vaporcomprises hydrogen peroxide or peracetic acid vapor. The contacting stepcan be by delivery via a method such as injection, static soak, liquidflow-through, aerosol spray, condensation or physical placement. Plasmacan also be used during the step of exposing the lumen to negativepressure. If plasma is used, the method can be performed within a sealedchamber and the plasma generated within the container. Thus, the methodcan be performed within a first chamber and the plasma generated in asecond, separate chamber and the plasma flowed into the first chamber.The diffusion-restricted container can have at least one exit tube, suchas one that is at least 1.0 cm in length and has an internal diameter of9 mm or less. The exit tube can also include a filter. In a preferredembodiment, the filter is sufficient to prevent entry of bacteria fromthe environment into the container. The source of peroxide can be usedat a concentration of less than 25% by weight. The exposing step ispreferably performed for 60 minutes or less. The method can be conductedalong with the step of heating the article during the exposing step.Thus, the exposing step can be conducted within a chamber, and thechamber heated during the exposing step. The exposing step can beconducted at a negative pressure between 0 and 100 Torr. Advantageously,the various steps of this method can also be repeated one or more times.

[0017] Still one more aspect of the invention relates to a method formaking a sterilized article within a diffusion-restricted container.This method includes contacting the article with a source of peroxide,and placing the article in the diffusion-restricted container in eitherorder. If the initial contacting step precedes the placing step, thecontacting step can be repeated after the placing step. These steps arefollowed by exposing the diffusion-restricted container to negativepressure for a time period sufficient to effect complete sterilizationof the article. The container used in this aspect of the invention hasat least one exit tube. The exit tube preferably has a filter thereinwhich is preferably sufficient to prevent entry of bacteria into thecontainer. The exit tube is at least 1.0 cm in length and/or has aninternal diameter of 9 mm or less. Advantageously, the exposing step,the contacting step, or the entire method can be repeated one or moretimes. In a preferred embodiment, the contacting step comprises deliveryvia injection, static soak, liquid flow-through, aerosol spray,condensation or physical placement. The container can be exposed to aplasma during the step of exposing the container to negative pressure.In one embodiment, the method is performed within a sealed chamber andthe plasma is generated within the chamber. The exposing step ispreferably performed for 60 minutes or less and/or at a pressure between0 and 100 Torr. The container can be heated during the exposing step, orthe source of peroxide heated prior to the contacting step. Theinvention also includes the sterilized article within adiffusion-restricted container produced by the method of this aspect. Inone embodiment, the source of peroxide comprises a liquid or condensedvapor. In another embodiment, the source of peroxide comprising a liquidcomprises hydrogen peroxide or peracetic acid. In another embodiment,the source of peroxide comprising a condensed vapor comprises hydrogenperoxide or acetic acid vapor.

[0018] Still one more aspect of the invention relates to a method formaking a sterilized article within a diffusion-restricted container.This method includes placing the article in the diffusion-restrictedcontainer and contacting the container with a source of peroxide, ineither order. These steps are followed by exposing thediffusion-restricted container to negative pressure for a time periodsufficient to effect complete sterilization of the article. Thecontainer used in this aspect of the invention has at least onecommunication port comprising an exit tube or air and vapor permeablewindow. The exit tube preferably has a filter therein which ispreferably sufficient to prevent entry of bacteria into the container.The exit tube is at least 1.0 cm in length and/or has an internaldiameter of 9 mm or less. The communication port is preferably connectedthrough a connector to the article to be sterilized, so that sterilantvapor may flow through the article and out of the container. Theconnector is preferably tubing or an adaptor which can be attached to alumen of said article, or an enclosure which contains a portion of thearticle with the lumen. In one embodiment, the exit tube is additionallyconnected to a valve outside the container and the valve is connectedwith a vacuum source. In one embodiment, the communication portcomprising a window is impermeable to microorganisms. Advantageously,the exposing step, the contacting step, or the entire method can berepeated one or more times. In a preferred embodiment, the contactingstep comprises delivery via injection, static soak, liquid flow-through,aerosol spray, condensation or physical placement. The container can beexposed to a plasma during the step of exposing the container tonegative pressure. In one embodiment, the method is performed within asealed chamber and the plasma is generated within the chamber. Theexposing step is preferably performed for 60 minutes or less and/or at apressure between 0 and 100 Torr. The container can be heated during theexposing step, or the source of peroxide heated prior to the contactingstep. The invention also includes the sterilized article within adiffusion- restricted container produced by the method of this aspect.In one embodiment, the source of peroxide comprises a liquid, a solid orcondensed vapor. In another embodiment, the source of peroxidecomprising a liquid comprises hydrogen peroxide or peracetic acid. Inanother embodiment, the source of peroxide comprising a solid comprisesa urea peroxide complex or sodium pyrophosphate peroxide complex or likecomplex. In another embodiment, the source of peroxide comprising acondensed vapor comprises hydrogen peroxide or acetic acid vapor.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019]FIG. 1 is a cross-sectional illustration of a lumen containing aninoculated stainless steel blade placed within a glass tube having onlya narrow opening to create a diffusion-restricted environment fortesting the sterilization method of the present invention.

[0020]FIG. 2 is a cross-sectional illustration of an inoculatedstainless steel blade placed directly within a glass tube having only anarrow opening to create an alternate diffusion-restricted environmentfor testing the sterilization method of the present invention.

[0021]FIG. 3 is a cross-sectional illustration of an inoculatedstainless steel blade placed directly within a glass tube having afilter placed at its narrow opening to create an alternatediffusion-restricted environment for testing the sterilization method ofthe present invention.

[0022]FIG. 4 is a cross-sectional illustration of one embodiment of adiffusion restricted environment represented by a container having alimited diffusion port (communication port consisting of tubing).

[0023]FIG. 5A is a cross-sectional illustration of one embodiment of adiffusion restricted environment represented by a container having alimited diffusion port (communication port consisting of tubing or thelumen device) and a tubing connector to connect a lumen device to thecommunication port of the container.

[0024]FIG. 5B is a cross-sectional illustration of one embodiment of adiffusion restricted environment represented by a container having alimited diffusion port (communication port consisting of tubing or thelumen device) and an enclosure connector to connect a lumen device tothe communication port of the container.

[0025]FIG. 6 is a cross-sectional illustration of one embodiment of adiffusion restricted environment represented by a container having alimited diffusion port and an enclosure connector to connect a lumendevice to the window.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0026] Sterilizing the inside of lumened devices has always posed achallenge to sterilization systems. Achieving rapid sterilization oflumened devices or other diffusion restricted articles at lowtemperatures and low concentrations of sterilant represents an evengreater challenge. In the present invention, the shortcomings of theprior art sterilization systems are overcome by pretreating orcontacting articles to be sterilized with a source of peroxide prior toexposure to a vacuum, or optionally, plasma. Alternatively, adiffusion-restricted environment containing articles to be sterilizedcan be contacted with a source of peroxide prior to exposure to avacuum. The source of peroxide comprises a liquid or condensed vapor inthe case wherein an article is contacted. In the case wherein adiffusion-restricted environment is contacted, the source of peroxideadditionally comprises a solid. The liquid comprises aqueous solutionsof hydrogen peroxide or peracetic acid. The solid comprises a ureaperoxide complex, or sodium pyrophosphate peroxide complex or likeperoxide complex. The vapor comprises hydrogen peroxide or peraceticacid vapor. The preferred method of the present invention utilizesaqueous hydrogen peroxide as the source of peroxide to contact anarticle to be sterilized. The methods of the present invention providefor the rapid sterilization of lumened and non-lumened articles underconditions that will not damage the articles nor leave toxic residues onthe sterile articles.

[0027] In the method of the present invention, the source of theperoxide is delivered into direct contact with the article to besterilized or with the diffusion-restricted environment containing thearticle to be sterilized. In the case of a lumened device, the source ofperoxide may be delivered directly into the lumen. In the case of anarticle having an area where diffusion of vapor is restricted, thesource of peroxide may be delivered to the interior of the diffusionrestricted area. For articles which are not diffusion-restricted, thesource of peroxide can be introduced anywhere into thediffusion-restricted environment. The source of peroxide is deliveredinto the lumen or into contact with the article to be sterilized or intocontact with the diffusion-restricted environment containing the articleto be sterilized through means such as direct delivery or physicalplacement, a static soaking process, a liquid flow-through process, byaerosol spray or by condensation of a vapor. Physical placement alsoincludes placement of a reservoir containing the source of peroxide. Inthe preferred method of the present invention, the aqueous solutions ofhydrogen peroxide can be relatively dilute, e.g., as low as 1-6% orlower by weight, since sterilization is not achieved through contactwith the hydrogen peroxide solution, but rather, is achieved at lowtemperatures and in short periods of time upon exposure to hydrogenperoxide vapor under vacuum or vacuum combined with plasma. The methodof the present invention is particularly effective with articles havinginaccessible or hard-to-reach places. Such articles include long, narrowlumens, hinges, and other articles having spaces where diffusion ofvapors is restricted.

[0028] The general operation of one embodiment of a preferred method ofthe present invention, which is useful for sterilizing the inside oflong, narrow lumens, is as follows:

[0029] 1. The lumen to be sterilized is contacted with a source ofperoxide. The source of peroxide can be physically delivered as a smallamount directly into the lumen, or by static soaking, liquidflow-through, aerosol spray or condensation of a vapor.

[0030] 2. The lumen to be sterilized is placed within a chamber, and thechamber is sealed and evacuated. (The source of peroxide can also bedelivered to the inside of the article after placing the article in thechamber.)

[0031] 3. The lumen is exposed to the vacuum for a period of time and ata temperature sufficient to effect sterilization.

[0032] 4. The sterile lumen is removed from chamber.

[0033] In an alternative embodiment of the method of the presentinvention, a similar method is used to sterilize both the inside andoutside of an article. In this alternative embodiment, the article to besterilized is placed in a diffusion-restricted environment. Thediffusion-restricted environment can be a rigid container or flexiblepouch having at least one exit tube. In this embodiment, the exit tubeis preferably diffusion-restricted. Alternatively, it is not necessarythat the exit tube be diffusion-restricted so long as diffusion ofsterilant vapor is limited by the article to be sterilized, such as thecase wherein sterilant vapor must flow through a limited diffusion areaor lumen of an article to be sterilized. This depends upon theconfiguration of the container. The exit tube may be constructed from avariety of materials, such as glass, metals and plastics and may includea filter. The filter may be sufficient to prevent entry of bacteria fromthe environment into the container. The source of peroxide is introducedto the inside of the article. The source of peroxide can be introducedeither before or after placing the article in the diffusion-restrictedenvironment. The diffusion-restricted environment containing the articleto be sterilized is then placed in the chamber, exposed to vacuum andremoved as in steps 2 through 4 above.

[0034] The general operation of an alternative embodiment of the methodof the present invention, which is also useful for sterilizing theinside of long, narrow diffusion-restricted lumens, is as follows:

[0035] 1. The article to be sterilized is placed in adiffusion-restricted environment such as a container, said containercomprising at least one communication port comprising an exit tube orair and vapor permeable window; and

[0036] 2. The diffusion-restricted environment is contacted with asource of peroxide, steps 1. and 2. being performed in either order;followed by

[0037] 3. The diffusion-restricted environment is exposed to negativepressure for a time period sufficient to effect complete sterilizationof said article.

[0038] The communication port is preferably connected through aconnector to the article, so that sterilant vapor may flow through thearticle and out of the container. In this embodiment, the communicationport comprising an exit tube or air and vapor permeable window is alsopreferably diffusion-restricted. Alternatively, it is not necessary thatthe communication port, in particular an air and vapor permeable window,be a limited diffusion port so long as diffusion of sterilant vapor islimited by the article to be sterilized, such as the case whereinsterilant vapor must flow through a limited diffusion area or lumen ofan article to be sterilized. This depends upon the configuration of thecontainer. The exit tube may be constructed from a variety of materials,such as glass, metals and plastics and may include a filter. The filtermay be sufficient to prevent entry of bacteria from the environment intothe container. The air and vapor permeable window may be constructedfrom permeable materials such as Tyvek.

[0039] In yet another alternative embodiment of the present inventionwhich pertains to all of the above methods, the article to be sterilizedis exposed to a vacuum followed by low temperature plasma for a timesufficient to effect sterilization. When used in the presentspecification and claims, the term “plasma” is intended to include anyportion of the gas or vapor that contains electrons, ions, freeradicals, dissociated and/or excited atoms or molecules produced as aresult of an applied electric field, including any accompanyingradiation that might be produced. The applied field may cover a broadfrequency range; however, a radio frequency or microwaves are commonlyused.

[0040] The sterilization methods of the present invention can also beused with plasmas generated by the method disclosed in the previouslymentioned U.S. Pat. No. 4,643,876. Alternatively, the methods of thepresent invention may be used with plasmas described in U.S. Pat. Nos.5,115,166 or 5,087,418, in which the article to be sterilized is locatedin a chamber that is separated from the plasma source.

[0041] The present invention provides several advantages over earliervapor sterilization systems, such as, (1) the rapid sterilization oflumened devices and diffusion restricted articles can be rapidlyachieved at low temperatures; (2) the use of concentrated, potentiallyhazardous, solutions of anti-microbials is avoided; (3) the need toattach a special vessel to deliver sterilant vapors into long, narrowlumens is eliminated; (4) no toxic residues remain; (5) since theproduct is dry at the end of the process, sterile storage of thesearticles can be achieved; (6) closed end lumens can be sterilized; and(7) the process can be repeated as desired without undue effects. Themethod of the present invention therefore provides for a highlyefficient, nonhazardous, and relatively inexpensive method ofsterilization.

[0042] To determine the efficacy of the preferred sterilization methodof the present invention, preliminary tests were first performed toevaluate the effect of dilute hydrogen peroxide solutions oncontaminated surfaces in an open, non-diffusion restricted environment.These tests are described below in Example 1.

EXAMPLE 1

[0043] To evaluate the sterilization efficacy of dilute hydrogenperoxide solution alone, a biological challenge consisting of 2.5×10⁶Bacillus stearothermophilus spores on a stainless steel scalpel bladewas used. Inoculated blades were submerged in 40 ml of hydrogen peroxidesolution in a 100 ml beaker. Four different concentrations of hydrogenperoxide solution were used: 3%, 6%, 9% and 12% by weight. The bladeswere allowed to soak in the peroxide solutions for various time periods.The blades were then removed from the solution and tested for sterility.The results of this testing are listed in Table 1 as a ratio of thenumber of inoculated blades which remain contaminated after treatmentover the number of inoculated blades tested. TABLE 1 Effect of H₂O₂Concentration and Soak Times on Sporicidal Activity of H₂O₂ SolutionConcentration of H₂O₂ Solution Soak Time 3% 6% 9% 12%  1 min 4/4 4/4 4/44/4  5 min 4/4 4/4 4/4 4/4  30 min 4/4 4/4 4/4 4/4  60 min 4/4 4/4 4/44/4  90 min N/D* 4/4 2/4 0/4 120 min N/D 4/4 N/D N/D

[0044] Complete sterilization was not effected until after the bladeshad been soaked in 12% hydrogen peroxide solution for at least 90minutes. Moreover, none of the blades tested were sterilized after 2hours in 6% hydrogen peroxide solution. It is clear from these data thatcontact with dilute hydrogen peroxide solution alone is ineffective atproviding sterilization, unless extended soak times and concentratedsolutions are used.

[0045] Testing was next performed to evaluate the effect on thesterilization of long, narrow lumens of a pretreatment step in which thelumens to be sterilized are exposed to hydrogen peroxide solution priorto exposure to a vacuum. The testing evaluated the efficacy of hydrogenperoxide vapor sterilization inside the lumens. The testing is detailedbelow in Example 2.

EXAMPLE 2

[0046] A biological challenge consisting of 1.9×10⁶ B.stearothermophilus spores on a stainless steel scalpel blade was used.Some inoculated blades were pretreated with a solution of aqueoushydrogen peroxide. Other inoculated blades, designated control blades,did not receive pretreatment with hydrogen peroxide. The pretreatmentconsisted of 5 minutes of static soaking in peroxide solution. Thepre-treated blades were blotted dry, and each blade was then placedinside a stainless steel lumen, 3 mm internal diameter (ID)×50 cmlength. The lumen had a center piece of 1.3 cm ID and 5 cm length. Thepretreated blade was placed inside this center piece, and additionalhydrogen peroxide solution was added into the center piece in variousamounts. Control blades were handled identically, except that they didnot receive pretreatment with hydrogen peroxide solution. The lumenswere placed in a vacuum chamber, and the chamber was evacuated to 1 Torrand held there for 15 minutes, during which time the temperatureincreased from approximately 23° C. to approximately 28° C. Followingexposure to the vacuum, the chamber was vented and the blades wereremoved from the chamber and tested for sterility. The results were asfollows: TABLE 2 Effect of Pretreatment and Hydrogen PeroxideConcentration on Sterilization of the Interior of Lumens Additionalperoxide ad- Blades not pre-treated Blades pre-treated in ded into thecenter piece with peroxide peroxide solution (A) With 1% hydrogenperoxide solution and vacuum  10 μL + +  20 μL + +  30 μL + +  40 μL + + 50 μL + + 100 μL + − 150 μL + − 200 μL − − 250 μL − − (B) With 3%hydrogen peroxide solution and vacuum  10 μL − −  20 μL − −  30 μL − − 40 μL − −  50 μL − − 100 μL − − 150 μL − − 200 μL − − 250 μL − − (C)With 6% hydrogen peroxide solution and vacuum  10 μL − −  20 μL − −  30μL − −  40 μL − −  50 μL − −

[0047] As seen from these results, sterilization can be effected usingrelatively dilute solutions of peroxide and exposure to negativepressure. When the vacuum was applied, the peroxide added to the centerpiece of the lumen was vaporized and contacted the blade, which wassufficient to effect sterilization. It can be seen from these data thatthe pretreatment increases effectiveness, but that pretreatment isunnecessary as long as the peroxide diffuses from the inside to theoutside,.

[0048] Sterilization inside various lumen sizes after pretreatment withperoxide was compared with sterilization inside the lumens without thepretreatment step. This testing is detailed in Example 3.

EXAMPLE 3

[0049] A biological challenge consisting of 1.9×10⁶ B.stearothermophilus spores on a stainless steel scalpel blade was used.Test A in Table 3 below consisted of the inoculated blades beingpretreated with a solution of 3% aqueous hydrogen peroxide. Thepretreatment consisted of 5 minutes of static soaking in the peroxidesolution. The pretreated blades were blotted dry, then placed into thecenter piece of a stainless steel lumen which varied in size, togetherwith 10 μl of 3% hydrogen peroxide solution. The center piece was 1.3 cmID and 5 cm length. Test B in Table 3 below consisted of identicallyinoculated control blades which did not receive pretreatment withhydrogen peroxide. Each inoculated control blade was placed directlyinto the center piece of a stainless steel lumen together with 10 μl of3% hydrogen peroxide solution. The center piece had dimensions identicalto those in Test A. Lumens of various dimensions were used to evaluatethe effect on sterilization of lumen internal diameter and length. Thelumens were placed in a vacuum chamber, and the chamber was evacuated to1 Torr for 15 minutes. During this 15 minutes of the sterilizationcycle, the temperature increased from approximately 23° C. toapproximately 28° C. Following exposure to the vacuum, the chamber wasvented and the blades were removed from the chamber and tested forsterility. The results are reported in Table 3, where “L/D Ratio”indicates the ratio of length to internal diameter. TABLE 3 Effect ofPretreatment With Dilute Hydrogen Peroxide in Various Sized Lumens SSlumen size L/D Ratio Test A Test B 1 mm × 50 cm 500 − − 1 mm × 40 cm 400− − 1 mm × 27 cm 270 − − 1 mm × 15 cm 150 − − 3 mm × 50 cm 166⅔ − − 3 mm× 40 cm 133⅓ − − 3 mm × 27 cm  90 − + 3 mm × 15 cm  50 + + 6 mm × 50 cm83⅓ − − 6 mm × 40 cm 66⅔ − − 6 mm × 27 cm  45 + + 6 mm × 15 cm  25 + +

[0050] All lumens having a L/D ratio greater than 50 which were testedunder the conditions of Test A of Example 3 were sufficientlydiffusion-restricted to be sterilized in this system. Thus, it isbelieved that other lumens having an UD ratio greater than 50 shouldalso provide a sufficient level of diffusion-restriction forsterilization in accordance with the present invention. This testingshows that, in direct contrast to prior art methods, sterility throughdiffusion of hydrogen peroxide vapor from inside the article to outsidethe article is easier to achieve in longer, narrower lumens than inshorter, wider lumens. This is believed to be due to the larger lumensallowing too much of the hydrogen peroxide vapor to diffuse out of theinside of the lumen during the sterilization process. Thus, the vapordoes not contact the internal surfaces for a period of time sufficientor at a concentration sufficient to effect sterilization.

[0051] As discussed above, prior art methods of hydrogen peroxide vaporsterilization of lumens are generally limited to use on relatively shortand wide lumens. In contrast to these prior art methods, the method ofthe present invention is effective on the interior of long, narrowlumens, including those longer than 27 cm in length and/or having aninternal diameter of less than 3 mm.

[0052] To determine whether the ability of the sterilant vapor todiffuse within the system is a critical factor in achieving sterility,additional testing was performed to compare diffusion restricted andopen, non-diffusion restricted systems. A non- diffusion restrictedsystem is one in which the diffusion of vapors in and around the articleis not restricted by narrow openings, long, narrow lumens, or the like.As used herein, “diffusion-restricted” refers to any one or more of thefollowing properties: (1) the ability of an article placed within thesterilization system of the present invention to retain 0.17 mg/L ormore hydrogen peroxide solution after one hour at 40° C. and 10 torr;(2) having the same or more diffusion restriction than provided by asingle entry/exit port of 9 mm or less in internal diameter and 1 cm orgreater in length; (3) having the same or more diffusion restrictionthan provided by a lumen 27 cm in length and having an internal diameterof 3 mm; (4) having the same or more diffusion restriction than providedby a lumen having a ratio of length to internal diameter greater than50; (5) the ability of an article placed within the sterilization systemof the present invention to retain 17% or more of the hydrogen peroxidesolution placed therein after one hour at 40° C. and 10 torr; or (6)being sufficiently diffusion-restricted to completely sterilize astainless steel blade within a 2.2 cm by 60 cm glass tube having arubber stopper with a 1 mm by 50 cm stainless steel exit tube therein ata vacuum of 10 torr for one hour at 40° C. in accordance with thepresent invention. It is acknowledged that characteristics (1) and (5)will vary depending on the initial concentration of hydrogen peroxideplaced into the article; however, this can be readily determined by onehaving ordinary skill in the art.

[0053] As discussed in the Background of the Invention, articles havingdiffusion restricted areas are difficult to sterilize using knownmethods of hydrogen peroxide vapor sterilization, since these methodsare dependent upon the diffusion of peroxide vapors from outside thearticle to the interior of the article. Testing performed to evaluatethe importance of sterilant vapor diffusion is described in Example 4.

EXAMPLE 4

[0054] Hydrogen peroxide vapor sterilization was tested in both open anddiffusion restricted systems. The open system consisted of stainlesssteel lumens having internal diameters of 1, 3, and 6 mm, and lengths of15, 27, 40 and 50 cm. Stainless steel scalpel blades were inoculatedwith 1.9×10⁶ B. stearothermophilus spores, and the blades placed in thecenter piece of the lumen together with 10 μl of 3% hydrogen peroxidesolution. The dimensions of the center piece were 1.3 cm ID, 5 cm lengthand 6.6 cc volume.

[0055] The diffusion restricted system is illustrated in FIG. 1.Identically inoculated scalpel blades 5 were placed within the centerpieces 10 of lumens 15 having dimensions identical to those describedabove. Ten μl of 3% hydrogen peroxide solution was also added to thecenter piece 10 of the lumen 15. The lumen 15 was then placed within a2.2 cm×60 cm glass tube 20. The tube 20 was closed at one end, and theopen end was plugged with a rubber stopper 25 having a 1 mm×10 cmstainless steel tube 30 inserted through the stopper 25. Thus, gasesentering or exiting the glass tube 20 could pass only through this 1mm×10 cm opening.

[0056] The open lumen system and the diffusion restricted system wereplaced inside a vacuum chamber. The chamber was evacuated to 1 Torrpressure and held there for 15 minutes, during which time thetemperature increased from approximately 23° C. to approximately 28° C.The chamber was then vented, and the blades removed from the lumens andtested for sterility. The results are as follows: TABLE 4 HydrogenPeroxide Vapor Sterilization in Open and Diffusion Restricted SystemsPeroxide System amount Length 1 mm ID 3 mm ID 6 mm ID Open 10 μL of 3%50 cm − − − 40 cm − − − 27 cm − + + 15 cm − + + Diffusion 10 μL of 3% 50cm − − − Restricted 40 cm − − − Environment 27 cm − − − 15 cm − − −

[0057] Under the test conditions of Example 4, sterilization was notachieved in the shorter, wider lumens in the open system withoutpre-treatment with hydrogen peroxide. Pre-treatment, and other testconditions, such as higher peroxide concentration or longer treatmenttime, would likely allow sterilization of the 27 cm×3 mm lumen, whichhas an LID ratio greater than 50. In the diffusion restricted system,the blades were sterilized in all sizes of lumens, using a 3% hydrogenperoxide solution.

[0058] These results indicate that providing a source of hydrogenperoxide within a diffusion restricted environment allows for completesterilization within the system. It is the restriction of vapordiffusion in the system, not the length or internal diameter of thelumen per se that determines the efficacy of the hydrogen peroxide vaporsterilization. Again, however, these data show that, unlike the priorart methods of hydrogen peroxide vapor sterilization of lumens, themethod of the present invention is effective even onnon-diffusion-restricted articles when placed into adiffusion-restricted environment.

[0059] To further test the idea that restriction of the diffusion ofvapor in a system affects the ability to sterilize the system, thefollowing experiment was performed.

EXAMPLE 5

[0060] A stainless steel scalpel blade 5 was placed within a 2.2 cm×60cm glass tube 20 which was closed at one end, as illustrated in FIG. 2.Each blade 5 had been inoculated with 1.9×10⁶ B. stearothermophilusspores. For some of the testing, the glass tube 20 was left open at oneend, providing an open system. To create a diffusion restrictedenvironment, the open end of the glass tube 20 was sealed with a rubberstopper 25 having a 1 mm×10 cm stainless steel tube 30 through itscenter. In both the open and diffusion restricted systems, hydrogenperoxide solution at a concentration of either 3% or 6% was added to theglass tube 20 in amounts of 50, 100, 150 or 200 μl, together with theinoculated blade 5. The tube 20 was placed in a vacuum chamber, and thechamber evacuated to 1 Torr for 15 minutes, during which time thetemperature increased from approximately 23° C. to approximately 28° C.The diffusion restricted system only was also tested at 1 Torr for 30minutes, during which time the temperature increased from approximately23° C. to approximately 33° C. The vacuum chamber was then vented, andthe blades 5 removed from the tube 20 and tested for sterility. Theresults are listed in Table 5 below. TABLE 5 Hydrogen Peroxide VaporSterilization in Open and Diffusion Restricted Systems 50 μL 100 μL 150μL 200 μL Open System, 15 minutes vacuum at 1 Torr: 3% peroxide + + + +6% peroxide + + + + Diffusion Restricted System, 15 minutes vacuum at 1Torr: 3% peroxide + − − − 6% peroxide − − − − Diffusion RestrictedSystem, 30 minutes vacuum at 1 Torr: 3% peroxide − − − −

[0061] These results show that the addition of hydrogen peroxidesolution, followed by exposure to vacuum, is ineffective for achievingrapid sterilization in an open system. Identical treatment in adiffusion restricted system, by comparison, results in completesterilization, except at the very weakest concentration of hydrogenperoxide solution in an amount of only 50 μl. Sterilization can beeffected, however, by increasing the exposure to the vacuum.

[0062] Thus, the method of the present invention, wherein small amountsof hydrogen peroxide solution are delivered to the article to besterilized prior to exposure to a vacuum, is an effective method ofsterilization. The method does not depend on the diffusion of sterilantvapor into the article being sterilized. Rather, the hydrogen peroxidevapor is created by the vacuum within the system. This vapor isprevented from leaving the system too quickly, because the diffusion ofthe sterilant vapor from the inside of the article to the outside of thearticle is slowed. In a diffusion restricted environment, the vaportherefore contacts the article to be sterilized for a period of timesufficient to effect complete sterilization. In addition, unlike theprior art methods where the water in the peroxide solution is vaporizedfirst and becomes a barrier to the penetration of the peroxide vapor,the method of the present invention removes any water from the systemfirst, thereby concentrating the hydrogen peroxide vapor remaining inthe system. More importantly, in the preferred method of the presentinvention, the diffusion of vapor is from the inside to outside ratherthan outside to inside as in the prior art. As a result, diffusion-restriction in the present invention serves to increase theeffectiveness of sterilization rather than to decrease theeffectiveness, as in the prior art.

[0063] To determine the effect of various pressures on a diffusionrestricted sterilization system, the following experiment was performed.

EXAMPLE 6

[0064] A stainless steel scalpel blade 5 was placed within a 2.2 cm×60cm glass tube 20 which was closed at one end, as shown in FIG. 2. Eachblade 5 had been inoculated with 1.9×10⁶ B. stearothermophilus spores.To create a diffusion restricted environment, the open end of the glasstube 20 was sealed with a rubber stopper 25 having a 1 mm×10 cmstainless steel tube 30 through its center. Hydrogen peroxide solutionat a concentration of 3% was added to the glass tube 20 in amounts of50, 100, 150 or 200 μl, together with the inoculated blade 5. The tube20 was placed in a vacuum chamber, and subjected to various pressuresfor 15 minutes, during which time the temperature increased fromapproximately 23° C. to approximately 28° C. In a further experiment todetermine the effect of increased temperature on the system, the tube 20was first heated to 45° C., then subjected to 50 Torr pressure for 15minutes. The results were as follows. TABLE 6 Effect of Temperature andPressure on a Diffusion Restricted System 50 μL 100 μL 150 μL 200 μL 15minutes vacuum with 3% hydrogen peroxide solution:  1 torr pressure + −− −  5 torr pressure − − − − 10 torr pressure − − − − 15 torr pressure −− − − 20 torr pressure − − − − 25 torr pressure − − − − 30 torrpressure + + + + 35 torr pressure + + + + 40 torr pressure + + + + 45torr pressure + + + + 50 torr pressure + + + + 15 minutes vacuum with 3%hydrogen peroxide at 45° C.: 50 torr pressure − − − −

[0065] These data show that sterilization can be achieved in diffusionrestricted environments at pressures up to about 25 Torr at 28° C. Atpressures of 30 Torr and higher, sterilization was not achieved; this isbelieved to be due to the fact that the vapor pressure of hydrogenperoxide at 28° C. is approximately 28 Torr. Thus, at higher pressures,the liquid hydrogen peroxide inside the glass tube was not vaporizing.This was confirmed by the testing done at 50 Torr pressure at 45° C.,wherein sterilization was achieved. The vapor pressure of hydrogenperoxide is increased at 45° C., thus, the hydrogen peroxide wasvaporized at 50 Torr, effectively sterilizing the blade placed insidethe tube.

[0066] Accordingly, in order to achieve sterilization using the methodof the present invention employing an aqueous solution of hydrogenperoxide, the temperature and pressure within the vacuum chamber shouldbe such that vaporization of the aqueous hydrogen peroxide solution isachieved, i.e. the system should preferably be operated below the vaporpressure of the hydrogen peroxide. The pressure needs to be below thevapor pressure of hydrogen peroxide, such that the hydrogen peroxidesolution present in the system is vaporized and diffuses from theinterior of the diffusion restricted environment to the outside.Alternatively, the hydrogen peroxide can be vaporized locally where thesystem remains above the vapor pressure by introducing energy to thesite of the peroxide, such as through microwaves, radio waves, or otherenergy sources.

[0067] To further determine the effect of varying the pressure and thetemperature in the diffusion restricted system described in Example 6,the following experiments were performed.

EXAMPLE 7

[0068] A stainless steel scalpel blade 5 was placed within a 2.2 cm×60cm glass tube 20 which was closed at one end, as illustrated in FIG. 2.Each blade 5 had been inoculated with 1.9×10⁶ B. stearothermophilusspores. To create a diffusion restricted environment, the open end ofthe glass tube 20 was sealed with a rubber stopper 25 having a 1 mm×10cm stainless steel tube 30 through its center. Hydrogen peroxidesolution at a concentration of 3% was added to the glass tube 20 inamounts of 50, 100, 150 or 200 μl together with the inoculated blade 5.The tube 20 was placed in a vacuum chamber, and the chamber evacuated to5 Torr. To vary the pressure within the chamber, the valve to the vacuumpump was closed, such that the pressure within the chamber rose from 5Torr to 6.15 Torr after 15 minutes, during which time the temperatureincreased from approximately 23° C. to approximately 28° C. In a secondtest, the tube 20 was placed in the chamber and the chamber wasevacuated to 50 Torr. The temperature of the glass tube 20 was increasedto 45° C. after the evacuation of the chamber was complete. The tube 20was treated for 15 minutes. The results of these tests are reportedbelow. TABLE 7 Effect of Varying Temperature and Pressure on DiffusionRestricted Sterilization System 50 μL 100 μL 150 μL 200 μL Pressureincreased from 5 Torr to 6.15 Torr: Efficacy Results − − − − Temperatureof the tube increased to 45° C.: Efficacy Results − − − −

[0069] These results show that maintaining a constant pressure ortemperature is not required in the diffusion restricted environment toeffect sterilization. Under the conditions tested, the hydrogen peroxideis vaporized and kept in contact with the device to be sterilized for atime sufficient to effect complete sterilization.

[0070] The preferred method of the present invention relies on thedelivery of liquid hydrogen peroxide to the article to be sterilizedprior to vacuum or plasma treatment. The following testing was performedto determine the effect of the location of the delivery of the hydrogenperoxide within the diffusion restricted environment.

EXAMPLE 8

[0071] A stainless steel scalpel blade 5 was inoculated with 1.9×10⁶ B.stearothermophilus spores, and the blade 5 placed in the center piece 10of a lumen 15 as illustrated in FIG. 1. The dimensions of the centerpiece 10 were 1.3 cm ID, 5 cm length and 6.6 cc volume, while the lumenitself varied in size, having an ID of 1, 3 or 6 mm, and a length of 15,27, 40 or 50 cm. The lumen 15 was placed within a 2.2 cm×60 cm glasstube 20. The tube 20 was closed at one end, and the open end was pluggedwith a rubber stopper 25 having a 1 mm×10 cm stainless steel tube 30placed through the stopper 25. Thus, gases entering or exiting the glasstube 20 could pass only through this 1 mm×10 cm opening. 10 μl of 3%hydrogen peroxide solution was placed inside the lumen 15, or 100 μl of3% hydrogen peroxide solution was placed inside the glass tube 20, butoutside the stainless steel lumen 15. The glass tube 20 was then placedin a vacuum chamber, which was sealed and evacuated to 1 Torr for 15minutes, during which time the temperature increased from approximately23° C. to approximately 28° C. Results of this testing are as follows.TABLE 8 Effect of Hydrogen Peroxide Solution Placed Outside Inner LumenPeroxide amount Length 1 mm ID 3 mm ID 6 mm ID 10 μL of 3% 50 cm − − −in lumen 40 cm − − − 27 cm − − − 15 cm − − − 100 μL of 3% 50 cm + + + inglass tube 40 cm − + + 27 cm + + + 15 cm + + −

[0072] These data show that, under the test conditions of Example 8,sterilization did not occur within the inner lumen when the hydrogenperoxide solution was placed outside the lumen in a diffusion restrictedenvironment, but that complete sterilization was effected when thehydrogen peroxide solution was placed inside all of the lumens in adiffusion restricted environment. When the hydrogen peroxide vapor mustdiffuse from outside to inside, the sterilant vapor cannot enter theinner lumen in a diffusion restricted environment unless the lumen issufficiently large.

[0073] Thus, when the hydrogen peroxide solution was placed outside thelumen, only the shortest, widest lumens allowed sufficient vaporpenetration to allow sterilization inside the lumen. These data confirmthat prior art methods which require diffusion of sterilant vapor fromoutside the article to the interior article cannot achieve sterilizationin diffusion restricted environments under these conditions. Incontrast, under the same conditions except where the hydrogen peroxidewas placed inside the article, allowing hydrogen peroxide to diffusefrom inside to outside, complete sterilization occurred with much loweramounts of hydrogen peroxide.

[0074] The method of the present invention is therefore useful inenvironments where diffusion of the sterilant vapor is limited. Toevaluate the effect of changes in the amount of diffusion restrictionwithin a diffusion restricted environment, the following testing wasperformed.

EXAMPLE 9

[0075] A stainless steel scalpel blade 5 was inoculated with 1.9×10⁶ B.stearothermophilus spores, and placed in a 2.2 cm×60 cm glass tube 20 asillustrated in FIG. 2. The tube 20 was closed at one end, and the openend was plugged with a rubber stopper 25. Stainless steel tubing 30 ofvarious dimensions was inserted through the stopper 25. Thus, gasesentering or exiting the glass tube 20 could pass only through theopening in the tubing 30, which varied from 1 mm to 6 mm in diameter.Three percent hydrogen peroxide solution in volumes ranging from 50 μLto 200 μl was also placed inside the glass tube 20. The glass tube 20was then placed in a vacuum chamber, which was sealed and evacuated to 5Torr for 15 minutes, during which time the temperature increased fromapproximately 23° C. to approximately 28° C. In addition, three lumenswere tested at 10 Torr for 15 minutes with 30% hydrogen peroxide. Theresults of this testing are listed below in Table 9. TABLE 9 Effects ofTubing Dimension and Vacuum Pressure on Sterilization 15 minutes vacuumat 5 Torr with 3% hydrogen peroxide SS tubing 50 μL 100 μL 150 μL 200 μL1 mm × 10 cm − − − − 1 mm × 5 cm − − − − 1 mm × 2.5 cm + − − − 3 mm × 10cm − − − − 3 mm × 5 cm − − − − 3 mm × 2.5 cm + − − − 6 mm × 10 cm − − −− 6 mm × 5 cm + − − − 6 mm × 2.5 cm + − − − 15 minutes vacuum at 10 Torrwith 3% hydrogen peroxide SS tubing 50 μL 1 mm × 2.5 cm − 3 mm × 2.5 cm− 6 mm × 2.5 cm −

[0076] Complete sterilization was achieved in the majority of theenvironments tested. Sterilization could not be achieved at 5 torr usingthe shortest length of Stainless steel tubing and only 50 μl hydrogenperoxide solution. Greater volumes of hydrogen peroxide must be used inthese systems.

[0077] These data also confirm that the vacuum pressure affectssterilization efficacy, since the container with the shortest and widestexit tube could provide sterilization at 10 Torr, but not at 5 Torr. Attoo low pressures (such as pressures below 5 Torr in the conditionstested) however, it appears that the hydrogen peroxide vapor is pulledfrom the interior of the article being sterilized too quickly, resultingin an insufficient amount of hydrogen peroxide vapor being allowed tocontact the interior of the device to effect sterilization. It wouldappear that although a pressure of 5 torr produces acceptable results, apressure of approximately 10 Torr is better under the conditions tested.

[0078] The method of the present invention has been shown to beeffective in diffusion restricted environments of metal and glass. Toevaluate whether the method is effective in diffusion restrictedenvironments formed of other materials, the experiments described inExamples 10 and 11 were performed.

EXAMPLE 10

[0079] For this testing, a diffusion restricted system was tested.1.2×10⁶ B. stearothermophilus spores were inoculated onto non-wovenpolypropylene pieces. As illustrated in FIG. 1, the inoculated pieces 5were placed inside the center piece 10 of a plastic lumen 15, togetherwith 10 μl of 3% hydrogen peroxide solution. The center piece 10 wasmade of Teflon™ and had dimensions of 1.3 cm×5 cm. The lumen 15 variedfrom 1 mm to 6 mm ID, and 15 cm to 50 cm in length. Teflon™ was used forthe 1 mm lumen, polyethylene was used for the 3 mm and 6 mm lumen. Thelumen 15 was then placed within a 2.2 cm×60 cm glass tube 20. The glasstube 20 was closed on one end, and the open end was sealed with a rubberstopper 25 having a 1 mm×10 cm piece of PTFE tubing 30 through it. Theglass tube 20 was placed in the vacuum chamber and treated for 15minutes at 1 Torr, during which time the temperature increased fromapproximately 23° C. to approximately 28° C. The results of this testingare set forth below. TABLE 10A Sterilization in Diffusion RestrictedSystems Using Plastic Lumens System Pressure Length 1 mm ID 3 mm ID 6 mmID Diffusion 1 torr 50 cm − − − Restricted 40 cm − − − System 27 cm − −− 15 cm − − −

[0080] Sterilization in diffusion restricted environments can beeffected in both short, wide lumens and long, narrow lumens, regardlessof whether metal or plastic is used to form the lumens. Thus, the methodof the present invention is an effective sterilization method fordiffusion restricted articles, and can be used on a wide variety of sucharticles, regardless of their composition.

[0081] To further confirm this, 2.1×10⁶ B. stearothermophilus sporeswere inoculated on stainless steel blades, and 1.2×10⁶ B.stearothermophilus spores were inoculated onto non-woven polypropylenepieces. As shown in FIG. 2, the blades 5 or non-woven polypropylenepieces 5 were placed inside a 2.2 cm×60 cm glass tube 20 together with50 μl of 3% hydrogen peroxide solution. One end of the tube was closed,and the open end was sealed with a rubber stopper 25 having either a 1mm×10 cm stainless steel tube 30 therein, or a 1 mm×10 cm piece ofTeflon™ tubing 30 therein. The glass tube 20 was placed inside a vacuumchamber and treated for 15 minutes at 5 Torr, during which time thetemperature increased from approximately 23° C. to approximately 28° C.The results are as follows TABLE 10B Effect of Metal and Plastic onSterilization in a Diffusion Restricted System SS tubing Teflon tubingMetal blade − − Polypropylene − −

[0082] Thus, all four combinations of metal and plastic provide foreffective hydrogen peroxide vapor sterilization in a diffusionrestricted environment. This testing confirms that the method of thepresent invention is an effective sterilization method for diffusionrestricted articles, and can be used on a wide variety of such articles,regardless of the materials used to form them.

[0083] Further testing was next performed to evaluate the effect ofvarious temperatures and pressures on the sterilization of a diffusionrestricted system. The testing is described below.

EXAMPLE 11

[0084] Stainless steel blades were inoculated with 2.1×10⁶ B.stearothermophilus spores. The blades 5 were placed inside a 2.2 cm×60cm glass tube 20 as illustrated in FIG. 2, along with various amounts of3% hydrogen peroxide solution. The glass tube 20 was placed in a vacuumchamber and subjected to different pressures and different temperaturesfor various periods of time. During the sterilization cycles reported inTable 11A, the temperature increased from approximately 23° C. to thetemperatures indicated. In the experiments reported in Table 11B, thechamber was heated to approximately 45° C. In an alternative embodiment,rather than heating the chamber, the temperature of the peroxidesolution itself can be heated. In the experiments reported in Table 11C,the temperature increased from approximately 23° C. to approximately 28°C. during the 15 minute period of exposure to vacuum. TABLE 11A Effectof Time and Volume of Peroxide on Sterilization in a DiffusionRestricted Environment At 5 Torr pressure: 5 min. 10 min. 15 min.(approx. (approx. (approx. 24° C.) 26° C.) 28° C.)  50 μL of 3% peroxide− − − 100 μL of 3% peroxide − − − 150 μL of 3% peroxide + − − 200 μL of3% peroxide + − −

[0085] TABLE 11B Effect of Elevated Chamber Temperature and Volume ofPeroxide on Sterilization in a Diffusion Restricted Environment Chamberat approximately 45° C.: 5 min. 150 μL of 3% peroxide − 200 μL of 3%peroxide −

[0086] TABLE 11C Effect of Pressure and Volume of Peroxide onSterilization in a Diffusion Restricted Environment With 15 minutesexposure time: Approx. 28° C. 1 torr 5 torr 10 torr  20 μL of 3%peroxide N/D + −  50 μL of 3% peroxide + − − 100 μL of 3% peroxide − − −

[0087] Under the test conditions of Example 11, large volumes ofhydrogen peroxide solution were ineffective at achieving sterilizationwhen vacuum was applied for only very short periods of time. This isbelieved to be at least partially because water vaporizes more quicklythan hydrogen peroxide. Thus, the water present in the aqueous solutionwill vaporize first, and more time is needed to vaporize the hydrogenperoxide. This also explains why the larger volumes of hydrogen peroxidesolution were effective at achieving sterilization at highertemperatures; the vaporization of the hydrogen peroxide occurs sooner athigher temperatures. Thus, when more water is present in the system,either higher temperatures or more time is required to achievesterilization.

[0088] Again, it would appear from these data that slightly higherpressures, i.e. 10 Torr, achieve more effective sterilization underthese conditions. This is believed to be because at higher pressures,more hydrogen peroxide vapor is retained inside the system. At too low apressure, the hydrogen peroxide vapor is pulled out of the system tooquickly.

[0089] In order to evaluate a putative minimum concentration of peroxidein the liquid/vacuum system in a diffusion-restricted container, Example12 was carried out.

EXAMPLE 12

[0090] Various concentrations of peroxide were used in a systemsubstantially as described in connection with FIG. 2. In this system,the exit tube 35 was a stainless steel tube having a length of 50 cm andan internal diameter of 1 mm. A stainless steel blade inoculated with1.9×10⁶ spores of B. stearothermophilus was placed within the containerwhich was a 2.2 cm×60 cm glass tube. Various amounts of 3% hydrogenperoxide were introduced into the container. The container was placed ina vacuum chamber of 173 liters, and the pressure reduced to 10 Torr fora period of one hour, during which time the temperature increased fromapproximately 23° C. to approximately 40° C. Sporicidal activity wasevaluated at each concentration of peroxide. In addition, the amount ofperoxide remaining in the container after the sterilization process wasevaluated by standard titration techniques, whereby the peroxide wasreacted with potassium iodide and titrated with sodium thiosulfate.Results are shown in Table 12 where “N/D” indicates not determined.TABLE 12 Amount of Peroxide Sporicidal Remaining in Glass Tube ActivityPeroxide 0.5 mg/L liquid + N/D 0.6 mg/L liquid + N/D 0.7 mg/L liquid +N/D 0.8 mg/L liquid + N/D 0.9 mg/L liquid + N/D 1.0 mg/L liquid − 0.17mg/L

[0091] The results reported in Table 12 indicate that 1.0 mg/L of 3%liquid peroxide were required in the system tested to effectsterilization. Further, under the conditions tested, a concentration of0.17 mg/L of peroxide remaining in the system was sufficient to providecomplete sterilization. These data also show that the glass tube used inthese experiments provided a sufficient level of diffusion restrictionto retain 17% of the hydrogen peroxide placed therein.

[0092] We further investigated the effects of length and internaldiameter of the exit tube used in a system similar to that of Example12. This testing is shown in Example 13.

EXAMPLE 13

[0093] A system similar to that described above in connection withExample 12, with the exception that 15 minutes of vacuum rather than onehour was used. Thus, the temperature increased only to about 28° C. Inthis testing, the size of the exit tube 35 was varied, as well as thevolume of 3% peroxide solution. The results are reported below in Table13. TABLE 13 50 μl 100 μl 150 μl 200 μl Open without tubing + + + +  6mm ID × 1 cm length + − − −  9 mm ID × 1 cm length + − − − 13 mm ID × 1cm length + + + +

[0094] The results show that provided sufficient peroxide is present,the diffusion- restriction provided by a single entry/exit port of 9 mmor less in internal diameter, or 1 cm or greater in length is sufficientto effect sterilization.

[0095] To further evaluate the effect on sterilization efficacy ofchanges in the amount of restriction of vapor diffusion in the system,the following testing was performed.

EXAMPLE 14

[0096] A stainless steel blade was inoculated with 2.1×10⁶ B.stearothermophilus spores. The blade 5 was placed inside a 2.2 cm×60 cmglass tube 20 as shown in FIG. 3, together with various amounts of 3%hydrogen peroxide solution. One end of the tube was closed, and the openend was sealed with a rubber stopper 25 having a syringe filter 35inserted therein. The glass tube 20 was placed inside a vacuum chamberand treated for 15 minutes at 5 Torr, during which time the temperatureincreased from approximately 23° C. to approximately 28° C. As acontrol, identically inoculated blades were placed inside 2.2 cm×60 cmglass tubes. The open end of the tubes was left open, no stopper orsyringe filter was used. Thus, the diffusion of vapor from the interiorof the tube was not restricted.

[0097] Various syringe filters having various pore sizes were tested,including MFS PTFE 25 mm syringe filters with a 0.2 μm membrane filterand a 0.5 μm membrane filter; a Nalgene PTFE 50 mm syringe filter with a0.2 μm membrane filter and a 0.45 um membrane filter; a Whatman Anotop™10 Plus sterile syringe filter with a 0.02 μm membrane filter and a 0.1μm membrane filter; and finally, a Gelman Acrodisc™ CR PTFE syringefilter with a 0.2 μm, 0.45 μm, and a 1.0 μm membrane. The results are asfollows. TABLE 14 Sporicidal Activity of H₂O₂ Solution with Vacuum in aContainer Having a Syringe Filter 15 minutes vacuum and 3% hydrogenperoxide: 50 μL 100 μL 150 μL 200 μL (a) Without syringe filter andstopper:  5 Torr + + + + 10 Torr + + + + (b) With MFS ™ PTFE 25 mmsyringe filter: (1) 0.2 μm membrane filter  5 Torr + − − − 10 Torr − − −− (2) 0.5 μm membrane filter  5 Torr + − − − 10 Torr − − − − (3) With 2MFS ™ filters together at 5 Torr pressure Two 0.2 μm filters − Two 0.5μm filters − (c) With Nalgene ™ PTFE 50 mm syringe filter: (1) 0.2 μmmembrane filter  5 Torr − − − − 10 Torr − − − − (2) 0.45 μm membranefilter  5 Torr − − − − 10 Torr − − − − (d) With Whatman Anotop ™ 10 Plussyringe filter: (1) 0.02 μm membrane filter  5 Torr − − 10 Torr − − (2)0.1 μm membrane filter  5 Torr − − 10 Torr − − (e) With GelmanAcrodisc ™ CR PTFE syringe filter: (1) 0.2 μm membrane filter  5 Torr +− 10 Torr − − (2) 0.45 μm membrane filter  5 Torr + − 10 Torr − − (3)1.0 μm membrane filter  5 Torr + − 10 Torr − −

[0098] As is apparent from these results, certain brands of filters donot create a sufficiently diffusion restricted environment at 5 Torrpressure when only 50 μl of hydrogen peroxide solution is placed in thesystem. Other brands of filters did provide sufficient diffusionrestriction; these brands of filters had either longer lumens or smallerfilter pore size. Using larger volumes of peroxide solution, 10 Torrpressure, or serial filters enhances the efficacy of the sterilizationsystem. This is important, as filters, including ones made of Tyvek™,are often used in packaging of sterile articles to preventrecontamination with bacteria. These filters generally have a pore sizeof 1 μm or less, or in the case of Tyvek™, create a tortuous path whichbacteria cannot cross. In the present invention, filters can be used incombination with other packaging means to create a diffusion restrictedenvironment to effect sterilization, and the sterile article can remaininside the packaging during storage prior to use; the filter willprevent recontamination of the sterile article.

[0099]FIG. 4 is a cross-sectional illustration of one embodiment of adiffusion restricted environment represented by a container having alimited diffusion port or communication port consisting of tubing. Thiscommunication port 30 may have an air permeable microorganism barriersuch as a filter in order to maintain a sterility of the devices 15 and40 in the container 20 after the container 20 is removed from the vacuumsource. The non-lumen device 40 and the exterior of the lumen device 15can be sterilized with the peroxide vapor generated from the source ofperoxide within the container 20. In one method of efficientlysterilizing the interior of the lumen device 15, the peroxide vaporneeds to be generated within the lumen device 15. Therefore, the lumendevice 15 needs to be pre-treated with liquid peroxide.

[0100]FIGS. 5-6 illustrate other embodiments of the present inventionemploying other packaging means to create a diffusion-restrictedenvironment to effect sterilization. Another approach can be used tosterilize the interior of lumen device 15 without pre-treating theinterior of lumen device 15 with the source of peroxide. In order toflow the peroxide vapor generated inside container 20 through theinterior of lumen device 15, a connector can be used to connect thelumen device 15 to the communication port 30 of the container 20. FIGS.5A and 5B illustrate this approach. FIG. 5A is a cross-sectionalillustration of one embodiment of a diffusion restricted environmentrepresented by a container 20 having a limited diffusion port orcommunication port 30, consisting of tubing, and a tubing connector 45to connect a lumen device 15 to the communication port 30 of thecontainer 20. FIG. 5B is a cross-sectional illustration of oneembodiment of a diffusion restricted environment represented by acontainer 20 having a limited diffusion port (communication port 30consisting of tubing) and an enclosure connector 50 to connect a lumendevice 15 to the communication port 30 of the container 20. Theenclosure connector 50 has an interface 51 between the container 20 andthe enclosure connector 50. This interface 51 can be constructed inseveral different ways so as to allow a portion of the lumen device 15to be inserted into the connector enclosure 50, while maintaining an airand vapor pressure seal between parts 15 and 50. One way to achieve thisis with a camera shutter approach employing an iris diaphragm, such as aprecision iris diaphragm from Edmund Scientific . An optional spring canbe used to insure the closure of the shutter. Another way to achieve anacceptable interface is to employ two plates, wherein the area betweenthe two plates has a compressible material, such as a rubber material.The lumen device 15 can be placed between the two plates and the twoplates moved together to form a gas and vapor impermeable seal aroundthe lumen device 15. Optionally, a porous material like a sponge or airpermeable material may be utilized for the compressible material. Inthis case, some vapor sterilant can diffuse between the compressiblematerial and the lumen device. However, most of the sterilant vapor isforced to diffuse through the lumen device. Yet another way to achievean acceptable interface is to employ a hole or horizontal opening forone or more lumen devices 15, said hole or opening being a gas or liquidinflatable port. Thus, the connector can be a tubing adapter 45 whichcan be attached to the lumen device 15 or an enclosure 50 which containsa portion of the lumen device 15. Since one of the openings of the lumendevice 15 is connected to the communication port 30 with the connector45 or 50, the vaporized peroxide has to be evacuated through the lumendevice 15. Tubing connector 45 can be constructed of any materials suchas silicone, teflon, etc. which meet the thermal, pressure, gas andvapor compatibility requirements of the system. These sameconsiderations apply to materials utilized for other parts illustratedherein. Note that the limited diffusion port can be created by eitherthe communication port 30 or the lumen device 15.

[0101]FIG. 6 illustrates another possible arrangement. FIG. 6 is across- sectional illustration of one embodiment of a diffusionrestricted environment represented by a container 20 having acommunication port 30 consisting of a window with an air permeablebarrier and an enclosure connector 50 to connect a lumen device 15 tothe window 30. In this embodiment, the lumen device 15 is connected tothe connector 50 and is used as the device to create the diffusionrestricted area in the container 20. Therefore, the communication port30 in FIGS. 4, 5A and 5B can be replaced with an air permeable window 30if desired. This porous window 30 allows the diffusion of air and vapor,but prevents microorganisms from outside from contaminating thesterilized instruments 15 or 40 in the container or pouch 20. Under thereduced pressure environment, the peroxide vapor is first generated inthe container or pouch 20 and then diffuses through the lumen device 15into the connector 50. The entire connector 50 can be made of airpermeable material. FIG. 6 additionally illustrates how the reducedpressure is to be achieved. This is achieved via a port 55 in the vacuumchamber 65, said port being connected to a vacuum pump 60 to produce thereduced pressure environment. In order to test whether other sterilantscan also be used to effect sterilization in diffusion restrictedenvironments, the following testing was performed.

EXAMPLE 15

[0102] A stainless steel blade was inoculated with 1.9×10⁶ B.stearothermophilus spores. The blade 5 was placed inside a 2.2 cm×60 cmglass tube 20 as shown in FIG. 2, along with various amounts of 4.74%peracetic acid solution (Solvay Interox Ltd., Warrington, England). Theglass tube 20 was placed in a vacuum chamber and subjected to 5 Torrpressure for 15 minutes, during which time the temperature increasedfrom approximately 23° C. to approximately 28° C. The results of thistesting is shown below. TABLE 15 Sterilization With Peracetic Acid in aDiffusion Restricted System 50 μL 100 μL 150 μL 200 μL Efficacy Results− − − −

[0103] These results show that peracetic acid, in which hydrogenperoxide coexists, can also be used in the sterilization method of thepresent invention.

[0104] It was discovered that by delivering small amounts of hydrogenperoxide solution to an article to be sterilized prior to exposure tovacuum, sterilization could be effected at lower temperatures and inshort periods of time. The following testing was performed to evaluatedifferent methods of delivering hydrogen peroxide solution to thearticle to be sterilized. Further, the efficacy of vacuum treatment andplasma treatment following pretreatment with aqueous hydrogen peroxidewere compared. The testing is described in Example 16 below.

EXAMPLE 16

[0105] In a first series of tests, stainless steel blades wereinoculated with 2.5×10⁶ B. stearothermophilus spores. The blades wereplaced in the expanded center piece of a 3 mm×50 cm stainless steellumen. The lumen was placed in a 1000 ml beaker containing 800 ml ofhydrogen peroxide solution. The lumen was soaked for 5 minutes in 3%hydrogen peroxide solution. The number of surviving organisms followingthis initial soak was determined. The lumens were removed from thehydrogen peroxide solution and the outside blotted dry with papertowels. The inside of the lumens were dried by placing one end of thelumen into a flask and blowing with a three second burst of compressedair. The lumens were shaken, and the blowing and shaking repeated untilno more solution was blown out. Subsequently, the lumen was placed in asterilization chamber and exposed to either a vacuum of 0.5 Torr for 15minutes, or plasma for 15 minutes at 0.5 Torr. After 15 minutes ofvacuum, the temperature increased from approximately 23° C. toapproximately 28° C. The results are set forth below in Table 1 6A.TABLE 16A Effect of H₂O₂ Solution Soak on Sporicidal Activity inStainless Steel Lumens Prior to Either a Plasma or a Vacuum TreatmentNumber of Surviving Sterility Test Results Conc. H₂O₂ (%) OrganismsAfter Soak Soak + Soak + Soak Time 5 min Soaking Alone Alone VacuumPlasma 3.0 8.2 × 10⁵ 4/4 0/4 0/4

[0106] A five minute soak in 3% hydrogen peroxide solution was aneffective means for delivering the hydrogen peroxide into the lumenprior to vacuum or plasma treatment. As noted before, treatment withhydrogen peroxide solution only is ineffective to achieve sterilizationusing dilute solutions and short soak times. Delivery of hydrogenperoxide solution via static soaking is at least as effective a way todeliver the hydrogen peroxide as depositing small volumes directly intothe lumen of the device.

[0107] Flow-through delivery of hydrogen peroxide was tested next. Here,stainless steel blades were inoculated with 2.5×10⁶ B.stearothermophilus spores. The blades were placed in the expanded centerpiece of a 3 mm×50 cm stainless steel lumen. Hydrogen peroxide solutionat 3% concentration was delivered to the lumen at a flow rate of 0.1L/min, using a peristaltic pump. The lumen was dried as described above.Following pretreatment with hydrogen peroxide solution, the lumen wasthen placed in a sterilization chamber and exposed to either a vacuum of0.5 Torr for 15 minutes, or plasma for 15 minutes at 0.5 Torr. Theresults are set forth below in Table 16B. TABLE 16B Effects ofFlow-Through Delivery of H₂O₂ Solution on Sporicidal Activity Prior toEither a Vacuum or a Plasma Treatment in Stainless Steel Lumens Conc.H₂O₂ Number of Surviving Sterility Test Results (%) Organisms after FlowFlow + Flow + 5 min flow Alone Vacuum Plasma 3 6.2 × 10⁵ 0/4 0/4

[0108] Delivery of the hydrogen peroxide solution via constant flow isalso an effective way to deliver hydrogen peroxide to the system.

[0109] Finally, the effect of delivery of hydrogen peroxide by aerosolspray was tested. Stainless steel blades were inoculated with 2.5×10⁶ B.stearothermophilus spores. The inoculated blades were placed in theexpanded center piece of a 3 mm×50 cm stainless steel lumen. Threepercent hydrogen peroxide solution was delivered to the lumen via a 3second aerosol spray. Aerosol spray rate was determined to be 0.04L/min. After a 5 minute wait following pretreatment with hydrogenperoxide, the lumen was dried as described above and the lumen was thenplaced in a sterilization chamber and exposed to either a vacuum of 0.5Torr for 15 minutes, or plasma for 15 minutes at 0.5 Torr. The resultsare set forth below in Table 16C. TABLE 16C Effects of Aerosol Deliveryof H₂O₂ Solution on Sporicidal Activity Prior to Either a Vacuum or aPlasma Treatment in Metal Lumens Number of Surviving Sterility TestResults Conc. H₂O₂ Organisms after Aerosol + Aerosol + (%) Aerosol AloneVacuum Plasma 3 7.4 × 10⁵ 0/4 0/4

[0110] Flow-through of hydrogen peroxide as either a liquid solution oraerosol can also be achieved by introducing increased pressure at thedelivery end or decreased pressure at the exit end of the device to betreated.

[0111] It is evident from the data in Tables 16A-16C that all threemethods of delivering hydrogen peroxide solution to the article to besterilized provided for effective sterilization. Thus, it appears that anumber of different methods of delivery can be used, as long as thehydrogen peroxide solution is present in the system prior to exposure tovacuum or plasma.

[0112] Finally, the efficacy of pretreatment with hydrogen peroxideprior to a sterilization cycle which combines exposure to hydrogenperoxide vapor, vacuum, and plasma was evaluated. The testing was asfollows.

EXAMPLE 17

[0113] Stainless steel blades were inoculated with 2.5×10⁶ B.stearothermophilus spores. The blades were soaked in 3% hydrogenperoxide solution for either 1 or 5 minutes. The blades were then placedin the expanded center piece of a 3 mm×50 cm stainless steel lumen. Thelumen was then placed in a sterilization chamber which was evacuated toapproximately 0.5 Torr. The sterilization cycle consisted of 15 minutesof hydrogen peroxide vapor diffusion with a minimum of 6 mg/L hydrogenperoxide, followed by 15 minutes of plasma at 400 watts. Following theplasma treatment, the chamber was vented and the blades tested forsterility. The results are shown below. TABLE 17 Effects of H₂O₂Solution Soak on Sporicidal Activity in Stainless Steel Lumens Prior toa Hydrogen Peroxide Vapor and Plasma Cycle Sterility Test Results Conc.H₂O₂ Soak Time Soak Alone Soak + Cycle 3% 1 min 4/4 0/4 5 min 4/4 0/4

[0114] Processing the lumens in a hydrogen peroxide vapor and plasmacycle alone left an average of 30 surviving organisms per blade.Pre-treating the blades by soaking in 3% hydrogen peroxide solution for5 minutes alone left an average of 8.2 x 105 surviving organisms perblade. Thus, under these particular test conditions, a combination ofhydrogen peroxide vapor exposure and plasma exposure, which has beenfound to be effective for many articles, was ineffective in a diffusionrestricted environment. However, by pretreating the article to besterilized with dilute hydrogen peroxide solution prior to exposure tohydrogen peroxide vapor and plasma, complete sterilization can beachieved.

[0115] While the invention has been described in connection withpreferred liquid sterilant solutions containing hydrogen peroxide, itwill be appreciated by those having ordinary skill in the art thatequivalent sterilization methods can be adapted for other sources ofperoxide sterilants. In an alternative embodiment, a sterilant having avapor pressure lower than that of water or other solvent in which thesterilant may be provided is used. For such sterilants, it is onlyimportant that the vapor pressure be lower than that of the solventwithin the temperature ranges contemplated herein. In yet otherembodiments, a solid source of peroxide sterilant may be utilized. Suchliquid and solid sterilants can be adapted for the techniques describedherein with only minor adjustments made for the differences in vaporpressure between hydrogen peroxide and such other sterilant, as can bereadily determined by those having ordinary skill in the art. As long asthe local vapor pressure at the site of the sterilant is below the vaporpressure of the sterilant, sterilization can be achieved substantiallyas described hereinabove.

Conclusion

[0116] Achieving rapid sterilization of lumened devices at lowtemperatures using low concentrations of sterilants has, until now, beenexceedingly challenging. A superior method of sterilization has beendiscovered which overcomes the problems of the known methods. Bypretreating articles to be sterilized or a diffusion- restrictedenvironment containing the articles with a source of peroxide such as anaqueous solution of hydrogen peroxide prior to exposure to a vacuum,rapid sterilization can be achieved at low temperatures, without damageto the articles, without leaving toxic residues behind, and without theneed to attach special vessels. The method of the present invention isefficient, nonhazardous, and inexpensive as well.

What is claimed is:
 1. A system for sterilizing a lumen devicecomprising; a chamber; a source of germicide; and a container insidesaid chamber, said container comprising: at least one interface, whereinsaid at least one interface separates said container into at least afirst compartment and a second compartment; at least one communicationport in said container, wherein said at least one communication portprovides fluid communication between an interior of said container andan interior of said chamber; and at least one lumen device extendingacross said at least one interface, whereby said first compartment is influid communication with said second compartment through said at leastone lumen device.
 2. The system of claim 1 , wherein said at least oneinterface further comprises at least one opening.
 3. The system of claim2 , wherein said at least one opening is adjustable.
 4. The system ofclaim 2 , wherein said at least one opening comprises a material whichis permeable to germicide generated from said source of germicide,wherein said material is located at least in a contact area between saidat least one interface and said at least one lumen device.
 5. The systemof claim 1 , further comprising at least one vacuum pump to evacuatesaid chamber and/or said container.
 6. The system of claim 1 , whereinsaid source of germicide comprises hydrogen peroxide.
 7. The system ofclaim 1 , wherein said at least one communication port in said containercomprises a gas or vapor permeable barrier.
 8. The system of claim 7 ,wherein said gas or vapor permeable barrier is impermeable tomicroorganisms.
 9. A system for sterilizing a lumen device, said systemcomprising: an enclosure with an interface, wherein said interfaceseparates said enclosure into a first compartment and a secondcompartment; at least one lumen device extending across said interface,whereby said first compartment is in fluid communication with saidsecond compartment through said lumen device; a source of germicide insaid first compartment; and a communication port in said secondcompartment, wherein said communication port provides fluidcommunication between an interior and an exterior of said enclosure. 10.The system of claim 9 , wherein said interface further comprises atleast one opening.
 11. The system of claim 10 , wherein said at leastone opening is adjustable.
 12. The system of claim 10 , wherein said atleast one opening comprises a material which is permeable to germicidegenerated from said source of germicide, wherein said material islocated at least in a contact area between said interface and said atleast one lumen device.
 13. The system of claim 9 , further comprising avacuum pump in fluid communication with said communication port.
 14. Thesystem of claim 9 , wherein said source of germicide comprises hydrogenperoxide.
 15. The system of claim 9 , wherein said communication port insaid second compartment comprises a gas or vapor permeable barrier. 16.The system of claim 15 , wherein said gas or vapor permeable barrier isimpermeable to microorganisms.
 17. A method for sterilizing a lumendevice, said method comprising: separating an enclosure into a firstcompartment and a second compartment with an interface, wherein at leastone lumen device extends across said interface, whereby said firstcompartment is in fluid communication with said second compartmentthrough said at least one lumen device; providing a germicide in saidfirst compartment; evacuating said enclosure through said secondcompartment; and flowing germicide from said first compartment to saidsecond compartment through said at least one lumen device.
 18. Themethod of claim 17 , wherein said germicide comprises hydrogen peroxide.19. The method of claim 17 , wherein said interface comprises at leastone opening.
 20. The method of claim 19 , further comprising adjustingsaid at least one opening.
 21. The method of claim 19 , wherein said atleast one opening comprises a material which is permeable to saidgermicide, whereby a contact area between said interface and said lumenis contacted with germicide.